know one's onions

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know one's onions

/ˌnəʊ wʌnz ˈʌnjənz/ UK
/ˌnoʊ wʌnz ˈʌnj(ə)nz/ US

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Origin unknown.

verb knows one's onions · knowing one's onions · knew one's onions · known one's onions · know one's onion

informal Synonym of know one's stuff: to be knowledgeable about a given subject or task. Joe really knows his onions when it comes to cooking.
Similar: know one's stuff

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MLA

"know one's onions." Wiktionary, via Micwyn, micwyn.com/word/know%20one's%20onions. Accessed 6 Nov. 2026.

APA

know one's onions. (n.d.). In Wiktionary, via Micwyn. Retrieved November 6, 2026, from https://micwyn.com/word/know%20one's%20onions

Chicago

"know one's onions." Wiktionary, via Micwyn. Accessed November 6, 2026. https://micwyn.com/word/know%20one's%20onions.

BibTeX

@misc{know_one_s_onions_2026,
  title = {know one's onions},
  howpublished = {Wiktionary, via Micwyn},
  year = {2026},
  url = {https://micwyn.com/word/know%20one's%20onions},
  urldate = {2026-11-06}
}